/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package sf.database.datasource.lookup;

import sf.database.datasource.DataSourceLookup;
import sf.spring.util.Assert;

import javax.sql.DataSource;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

/**
 * Simple {@link DataSourceLookup} implementation that relies on a map for doing
 * lookups.
 * <p>
 * <p>
 * Useful for testing environments or applications that need to match arbitrary
 * {@link String} names to target {@link DataSource} objects.
 * @author Costin Leau
 * @author Juergen Hoeller
 * @author Rick Evans
 * @since 2.0
 */
public class MapDataSourceLookup implements DataSourceLookup {

    private final Map<String, DataSource> dataSources = new HashMap<String, DataSource>(4);

    /**
     * Create a new instance of the {@link MapDataSourceLookup} class.
     */
    public MapDataSourceLookup() {
    }

    /**
     * Create a new instance of the {@link MapDataSourceLookup} class.
     * @param dataSources the {@link Map} of {@link DataSource DataSources}; the keys are
     *                    {@link String Strings}, the values are actual {@link DataSource}
     *                    instances.
     */
    public MapDataSourceLookup(Map<String, DataSource> dataSources) {
        setDataSources(dataSources);
    }

    /**
     * Create a new instance of the {@link MapDataSourceLookup} class.
     * @param dataSourceName the name under which the supplied {@link DataSource} is to be
     *                       added
     * @param dataSource     the {@link DataSource} to be added
     */
    public MapDataSourceLookup(String dataSourceName, DataSource dataSource) {
        addDataSource(dataSourceName, dataSource);
    }

    /**
     * Set the {@link Map} of {@link DataSource DataSources}; the keys are
     * {@link String Strings}, the values are actual {@link DataSource} instances.
     * <p>
     * If the supplied {@link Map} is {@code null}, then this method call
     * effectively has no effect.
     * @param dataSources said {@link Map} of {@link DataSource DataSources}
     */
    public void setDataSources(Map<String, DataSource> dataSources) {
        if (dataSources != null) {
            this.dataSources.putAll(dataSources);
        }
    }

    /**
     * Get the {@link Map} of {@link DataSource DataSources} maintained by this
     * object.
     * <p>
     * The returned {@link Map} is {@link Collections#unmodifiableMap(Map)
     * unmodifiable}.
     * @return said {@link Map} of {@link DataSource DataSources} (never
     * {@code null})
     */
    public Map<String, DataSource> getDataSources() {
        return Collections.unmodifiableMap(this.dataSources);
    }

    /**
     * Add the supplied {@link DataSource} to the map of {@link DataSource
     * DataSources} maintained by this object.
     * @param dataSourceName the name under which the supplied {@link DataSource} is to be
     *                       added
     * @param dataSource     the {@link DataSource} to be so added
     */
    public void addDataSource(String dataSourceName, DataSource dataSource) {
        Assert.notNull(dataSourceName, "DataSource name must not be null");
        Assert.notNull(dataSource, "DataSource must not be null");
        this.dataSources.put(dataSourceName, dataSource);
    }

    @Override
    public DataSource getDataSource(String dataSourceName) throws DataSourceLookupFailureException {
        Assert.notNull(dataSourceName, "DataSource name must not be null");
        DataSource dataSource = this.dataSources.get(dataSourceName);
        if (dataSource == null) {
            throw new DataSourceLookupFailureException("No DataSource with name '" + dataSourceName + "' registered");
        }
        return dataSource;
    }

    @Override
    public Collection<String> getAvailableKeys() {
        return this.dataSources.keySet();
    }
}
